If wrap just happened we need to prevent emitting waits for pre wrap values. Detect this and emit no-ops instead. v2: Use olr > seqno to detect wrap instead of *seqno == 0 as suggested by Chris Wilson. v3: Use last used seqno to detect the wraparound. From Chris Wilson v4: Fixed unnecessary last_seqno assigment References: https://bugs.freedesktop.org/show_bug.cgi?id=57967 Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com> --- drivers/gpu/drm/i915/i915_drv.h | 2 +- drivers/gpu/drm/i915/i915_gem.c | 2 +- drivers/gpu/drm/i915/intel_ringbuffer.c | 26 +++++++++++++++++++++----- 3 files changed, 23 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 2ab476d..9da6782 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -671,7 +671,7 @@ typedef struct drm_i915_private { struct pci_dev *bridge_dev; struct intel_ring_buffer ring[I915_NUM_RINGS]; - uint32_t next_seqno; + uint32_t last_seqno, next_seqno; drm_dma_handle_t *status_page_dmah; struct resource mch_res; diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index e4b233d..a81b78a 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -1969,7 +1969,7 @@ i915_gem_get_seqno(struct drm_device *dev, u32 *seqno) dev_priv->next_seqno = 1; } - *seqno = dev_priv->next_seqno++; + *seqno = dev_priv->last_seqno = dev_priv->next_seqno++; return 0; } diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c index 0d03dc6..69bbe7b 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.c +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c @@ -596,6 +596,13 @@ gen6_add_request(struct intel_ring_buffer *ring) return 0; } +static inline bool i915_gem_has_seqno_wrapped(struct drm_device *dev, + u32 seqno) +{ + struct drm_i915_private *dev_priv = dev->dev_private; + return dev_priv->last_seqno < seqno; +} + /** * intel_ring_sync - sync the waiter to the signaller on seqno * @@ -626,11 +633,20 @@ gen6_ring_sync(struct intel_ring_buffer *waiter, if (ret) return ret; - intel_ring_emit(waiter, - dw1 | signaller->semaphore_register[waiter->id]); - intel_ring_emit(waiter, seqno); - intel_ring_emit(waiter, 0); - intel_ring_emit(waiter, MI_NOOP); + /* If seqno wrap happened, omit the wait with no-ops */ + if (likely(!i915_gem_has_seqno_wrapped(waiter->dev, seqno))) { + intel_ring_emit(waiter, + dw1 | + signaller->semaphore_register[waiter->id]); + intel_ring_emit(waiter, seqno); + intel_ring_emit(waiter, 0); + intel_ring_emit(waiter, MI_NOOP); + } else { + intel_ring_emit(waiter, MI_NOOP); + intel_ring_emit(waiter, MI_NOOP); + intel_ring_emit(waiter, MI_NOOP); + intel_ring_emit(waiter, MI_NOOP); + } intel_ring_advance(waiter); return 0; -- 1.7.9.5
